1. Field of the Invention
The present invention relates to an in-car-device controller equipped with a plurality of switch units issuing various control instructions. More particularly, the present invention relates to an in-car-device controller that automatically identifies the type of a switch unit and automatically conducts control instructed by the switch unit even if the switch unit instructing particular control is installed and operated in a different unit mount.
2. Description of the Related Art
Hitherto, the panel surface of an automobile instrument panel is provided with a plurality of manual switches for air conditioning in an automobile compartment. These manual switches are selectively operated to switch between a heating mode and a cooling mode of an air conditioner or to change a set temperature in an automobile compartment.
In recent years, there has been a demand for installing one or plural optional manual switches for operating optional devices on the panel surface of an instrument panel, in addition to the group of manual switches for air conditioning. Such a demand has arisen to deal with a variety of user options. To meet the demand, there has been proposed a switching device that accommodates a plurality of different types of optional manual switches.
This type of switch unit, which has conventionally been proposed, includes unit mounts to which a plurality of switch units equipped with optional manual switches can be installed. One switch unit or plural different types of switch units can be arbitrarily installed to the unit mounts. Regardless of the types of the switch units installed to the unit mounts, the functions of the installed switch units can be implemented by a central control unit (CPU) of a controller, which processes a switching signal received from the switch unit.
As this type of switch unit, there has been known another in-car device controller adapted to automatically identify the types of switch units when the switch units are installed to the unit mounts.
The known switch unit is provided with a recognition signal generating means for issuing a unique switch signal for each different switch when the switch is turned ON. Furthermore, a control circuit unit is provided with a switch identifying circuit that issues an output signal for driving a particular load in response to a recognition signal. The switch unit is configured to read a switch signal from the recognition signal generating means of a replaced cassette-type switch assembly by the switch identifying circuit. The recognition signal generating means has different internal interconnections for different types of switches. When a contact of a switch is closed, a switch signal uniquely assigned to that switch is output, and the switch signal serves as a recognition signal indicating the function of the switch. The switch identifying circuit has input terminals and logic circuits associated with output terminals of the switches to process switch signals received from the switches by the logic circuit so as to output drive signals to loads associated with the functions of the switches.
Thus, the switch unit obviates the need for changing the circuit configuration of a control circuit unit when installing or replacing a switch, and enables the operation associated with the function of each switch to be performed simply by changing a plurality of cassette-type switch assemblies which output unique switch signals.
On the other hand, however, the known switch unit discussed above poses the following disadvantage. The switch units are adapted to issue different switch signals from the recognition signal generating means by providing the switches with different interconnections. This means that there must be as many switches with different interconnections as different functions to be implemented. Hence, no general-purpose switches can be used, and the mounting positions of the switches on a printed circuit board must be changed for different functions, adding to manufacturing cost. Furthermore, the number of available combinations of interconnections in the switches is limited, and a switch identifying circuit naturally has limited combinations of logic circuits, making it difficult to accommodate increasing control functions.
The assignee has previously proposed some controllers for in-car devices to improve the disadvantages of the prior technologies described above.
A first controller for in-car devices that has been proposed is constructed by a plurality of different types of switch units that incorporate identifying elements having different circuit constants, and switch unit identifying sections for detecting values that depend on the circuit constants of the identifying elements thereby to identify the types of the switch units when they are attached to the unit mounts. The unit mounts of a second controller for in-car devices that has been proposed are equipped with a plurality of sets of switches having a plurality of driving pins that permit contacts to be independently switched. The shape of each keytop attached to each switch mounting section has a different shape, and a different combination of the driving pins can be used for each keytop so as to issue a different recognition signal from each different switch. A third controller for in-car devices that has been proposed is constructed by a plurality of types of switch units incorporating different diode connection circuits, and a switch unit identifying section that digitally identifies the type of a mounted switch unit by detecting an output signal of a diode connection circuit when the switch unit is mounted on the unit mount.
These in-car-device controllers obviate the need for providing switches with different interconnections, thus saving cost. The first and the third in-car-device controllers are capable of generating signals that can be identified by the switch unit identifying section in an extensive range by changing the identifying elements or the diode connection circuits, enabling them to accommodate more control functions.
However, as in the case of the in-car-device controllers previously proposed by the assignee, the conventional in-car-device controllers in which the controllers automatically identify the types of the switch units when the switch units are attached to the unit mounts are not provided with any means for stopping a control function that has been implemented by turning the switch unit ON if the switch unit is removed after being attached to the unit mount to carry out its function. This is inconvenient in that the function associated with the switch unit cannot be cleared unless the switch unit, that has once been detached, is placed back onto the unit mount to turn it OFF.
More specifically, according to the in-car-device controllers previously proposed by the assignee, if a switch unit is attached to one unit mount, the type of the switch unit is automatically identified by the control unit, and a predetermined control function is implemented by turning the switch unit ON. Thus, the switch unit is removed from the unit mount after turning the switch unit ON, and another type of switch unit is mounted on the same unit mount. The type of the newly attached switch unit is automatically recognized by the controller, and another control function is implemented by turning the newly attached switch unit ON. However, the preceding control function that has been implemented by the detached switch unit would continue to be carried out. To stop the previously implemented function, therefore, the switch unit that has been removed must be mounted back onto the unit mount to turn the function OFF.
Hence, in these conventional types of in-car-device controllers, another switch unit cannot be mounted unless it has been confirmed that the control function associated with a switch unit to be removed from the unit mount has been cleared. If a switch unit carrying out its associated control function is erroneously removed, then the switch unit has to be mounted back on to turn it OFF; otherwise, another switch unit cannot be mounted. Thus, the conventional types of controllers disadvantageously require great efforts in replacing the switch units.
The present invention has been made with a view toward solving the problems of the conventional art described above, and it is an object of the present invention to provide an in-car-device controller that allows a switch unit to be easily replaced.
To this end, according to a first aspect of the present invention, there is provided an in-car-device controller equipped with a plurality of types of switch units associated with different control functions, a control switch and a keytop constituting each one of the switch units, a plurality of unit mounts to which the switch units are individually installed, detection switches individually provided on the plural unit mounts, and a control unit that automatically identifies the types of the switch units mounted on the unit mounts, detects a detection switch signal issued from a detection switch when the switch unit or keytop constituting part of the switch unit is removed from a unit mount, and switches OFF at least the control function associated with the removed switch unit or keytop.
With this arrangement, when a switch unit or a keytop is removed from a unit mount, a detection switch is actuated to cause the control unit to automatically recognize that the switch unit or the keytop has been removed from the unit mount, and at least the control function associated with the removed switch unit or keytop is switched OFF. Therefore, a user does not have to check if the control function associated with a control switch has been turned OFF before removing a switch unit or a keytop from a unit mount. Moreover, there will be no need to mount a switch unit or a keytop back onto a unit mount after it has been is removed. Thus, the switch units can be replaced more easily in an in-car-device controller adapted to automatically identify the type of a switch unit by the control unit when the switch unit is attached to a unit mount.
According to a second aspect of the present invention, there is provided an in-car-device controller equipped with a plurality of types of switch units individually associated with different control functions, a plurality of unit mounts to which the switch units are individually installed, a single cover installed on a front surface of each of the plural unit mounts such that it can be opened and closed, a cover detection switch for detecting the opening and closing of the cover, and a control unit that automatically identifies the type of a switch unit attached to the unit mount, detects a cover detection switch signal output from the cover detection switch when the cover is opened, and switches OFF the control functions associated with all switch units that have been attached to the unit mounts.
With this arrangement, whenever a switch unit or a keytop is removed from a unit mount, the cover is opened first, since the cover is provided on the front of the unit mount. Hence, an output signal of the cover detection switch interlocked with the cover is detected, and the control functions associated with all switch units attached to the unit mounts are automatically turned OFF. This makes it possible to provide the same advantages described above simply by adding a single detection switch, and the configuration of an in-car-device controller can be further simplified.